The "...+" means "takes at least one argument".
> (+)
0
> (max)
max: expects at least 1 argument, given 0
>
I think the preferred way to check for inexact equality is to compare
the absolute difference with a small tolerance, like you were looking for.
(require rackunit)
(define (inexact=? a b epsilon)
((abs (- a b)) . < . epsilon))
(check-false (inexact=? 1 2 0.1))
(check-true (inexact=? 1 1.05 0.1))
There are more sophisticated ways to do this, but they're harder to
understand and I've never seen them implemented in a math library.
Neil T
On 10/03/2011 10:55 AM, John Riedl wrote:
In section 3.2.2 of the online Racket documentation a number of the
signatures of the functions end with "+", e.g.,:
(max x ...+) → real?
Most signatures do not have the +, including those that take an
arbitrary number of arguments, e.g.,:
(+ z ...) → number?
Do the plus signs mean anything, or are they just typos?
(The reason I was looking is to see if there is a version of equal?
that takes a tolerance, like check-=? from rackunit. What is the
preferred way to check equality for inexact numbers?)
Thanks!
John
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